Over the years, various techniques and devices have been developed to help a person accurately aim a firearm such as a rifle or a target pistol. One common approach is to mount on the barrel of the firearm a sight or scope, through which a person views the intended target in association with a reticle, often with a degree of magnification. In this regard, firearm sights sometimes include a tumbler having optics thereon, the tumbler being movable between two different positions in which the sight provides different levels of magnification of an image viewed by the person using the sight. Although existing firearm sights of this type have been generally adequate for their indented purposes, they have not been satisfactory in all respects.
As one aspect of this, it is common to provide one or more adjustments for the position of the movable tumbler, to effect calibration that aligns the optics on the tumbler with other optics within the sight. For example, there may be a tilt adjustment and/or an elevation adjustment for the tumbler. Existing arrangements for adjusting the position of a movable tumbler tend to involve a significant number of parts, as a result of which they are more expensive and less compact than would be desirable.
As another aspect, a manually-operable mechanism is normally provided to move the tumbler between its operational positions. In pre-existing mechanisms, inadvertent manual contact or a physical shock could cause the mechanism to effect an unintended release that permits the tumbler to move away from a selected position, sometimes to an intermediate position that is not a valid operational position of the tumbler and that effectively renders the sight optically non-operational. In a combat situation, it can be potentially dangerous for a soldier using the weapon if an unexpected movement of the tumbler either changes the magnification to a setting that is not currently useful, or renders the sight optically non-operational. A further consideration is that pre-existing mechanisms tend to be physically larger than desirable, and are integrated into the sight in a manner making it difficult to assemble the sight during production, and/or to disassemble and reassemble the sight if repairs are needed.